DK174442B1 - Method for regulating an electrolysis cell - Google Patents

Abstract

This cell comprises means for measuring and controlling the entry and exit flow rates, the temperature of the electrolyte, the various concentrations and the current; all these means are connected to a calculating system which determines what are the most probable values of the flow rates, concentrations and current, which is called a coherence treatment, and thus delivers signals to the controlling means. This process is particularly useful for the electrolysis of NaCl in the production of chlorine and sodium hydroxide.

Description

DK 174442 B1

The present invention relates to a method for regulating an electrolysis cell. One uses e.g. by electrolysis aqueous solutions of sodium chloride, which is the only industrial process for the preparation of chlorine and of sodium hydroxide.

In short, instead of, for example, centralizing. to use a velocity measurement to affect a regulation of velocity and at the same time a concentration measurement to affect a temperature controller, all measurements, these measurements are summarized with the total account of the cell and 10 signals are sent to different regulators.

Electrolysis is a method used industrially for e.g. to produce alkali metal chlorates or alkali metal hydroxides. The electrolysis of sodium chloride solutions to produce chlorine and sodium hydroxide is the most important in terms of quantities produced and because it is the only industrial process used today, see e.g. KIRK-OTHMER, Encyclopedia and Chemical Technology, 3rd edition pages 799 to 865.

It is known that the regulation of the function of an electrolytic cell or of a system of electrolytic cells is generally achieved by a control system which uses the values of parameters provided by collection sensors characteristic of the particular element (s) or connections (s). with the supply or when leaving the plant. These values make it possible to regulate the operation of the system thanks to means of regulation to which a control signal is applied, as well as signals corresponding to some of the parameters (eg the contents of residual compounds at the output of the system). These means of regulation provide a control signal which, in particular, allows the means of controlling the speeds of the connections to the plant to be controlled.

30

This type of control, which is well known in the prior art, uses at least one control loop and exhibits the disadvantages that result from the values of the parameters delivered by the sensors being values which are adapted to these parameters. characteristics and not very exact values.

As a result, a control device operating directly from the values of the characteristic parameters provided by the sensors will not allow an optimal control order to be obtained so that an electrolyte cell operates at the optimum yield.

In the prior art, control systems specific to electrolysis cells are disclosed. U.S. Patent No. 4,035,268 discloses a device for controlling the spacing of the electrodes in a cell by a method referred to as the "mercury method". European patent no. EP 99795 discloses a system for regulating the current in a system of electrolysis cells. As before, these devices are only improved conventional control systems, viz. that you have analyzed and measured more accurately a parameter and that you have sent it to a conventional regulator.

15

The present invention has for its object to overcome the disadvantages of known devices for regulating the function of an electrolytic cell, in particular by taking into account the values of a large number of parameters and by a corrective calculation of the values of these parameters, in a manner such as makes it possible to regulate the operation of the plant to obtain maximum yield. This corrective calculation is actually a so-called coherence calculation of the values of the measured parameters.

The present invention thus relates to a method for regulating an electrolytic cell of the kind mentioned in claim 1, and this method is characterized by the part of claim 1.

By the term electrolysis cell is understood any device in which at least one chemical reaction is effected under the influence of a difference in potential and of a current provided by an electricity generator; it is about e.g. on the electrolysis of sodium chloride to produce sodium chlorate, of hydrogen fluoride to produce elemental fluorine or sodium chloride in aqueous solution to produce chlorine and sodium hydroxide, which is known as "chloro-alkali electrolysis". This chlor-alkali electrolysis is generally carried out according to 3 methods, all 3 being used under industrial conditions, namely: - the mercury method, - the diaphragm method, and - the membrane method.

The term "electrolysis cell" also designates a system of electrolysis cells.

10 The feed product is understood to mean any material flow which enters the cell, e.g. natriumchioridopløsningen. By analogy, the exit product denotes a flow of material leaving the cell; the solution of sodium hydroxide and sodium chloride by a diaphragm method or the solutions of sodium hydroxide and the solutions of sodium chloride of lower content in the membrane and mercury methods. The gaseous stream, which is essentially formed of hydrogen, is e.g. also a leaving product in front of a cell in the chlor-alkali electrolysis. The means for measuring (a) denote any conventional measuring system for a velocity of a gas or a liquid, such as a diaphragm, a venturi device or a counting apparatus. All of these systems 20 provide a signal representing the speed, the signal may be in electrical form, such as a voltage or current, and it may be either an analog signal or a numerical signal, or it may also be in radio-electric form. It can also be a pneumatic signal which can be converted into an electrical signal.

25

The means of regulation (b) are e.g. means which act upon variation of the loss of load for a product at the time of application or at the outlet. Pneumatic valves or electro valves are generally used. Variable speed pumps can also be used.

30

The means (c) for measuring the temperature of the electrolyte are per se known means, they may be located in the cell close to the electrodes or on a piping in which the electrolyte passes at the entrance to or at the exit from the cell.

, DK 174442 B1 4

They, like the means (a) provide signals, most often electrical signals which represent the temperature. Means for controlling the temperature of the electrolyte may be selected from the means known per se for heat exchange, or one may also influence the temperature of the electrolyte upon entry into the cell by these means.

The calculating means (d) are also known per se, and they include e.g. electronic circuits for analog calculations or numerical calculations or analog and numerical calculations and they are connected to the means for measuring (a) and (c) by conventional wires. The calculating means (d) are preferably computer-type devices capable of performing numerical and logical operations in accordance with pre-entered instructions and in accordance with pre-entered values, and values or information supplied by means of measurement (a) and (c). ).

These computational means (d) are preferably supplemented by means of visual display such as screens or printers and means for storing the information such as magnetic means.

The current in the cell denotes the electrical current measured 20 between the electrodes, or e.g. between the anodes and the mercury bed, in the case of mercury cell. "Current" also denotes the current of a system of cells. The means for measuring the current are conventional means, as used by electrical professionals, as are the means for regulating this current. One can, for example, regulate the current. apply an effect on the voltage of the diodes, or on the rectifier (s) used, or also on the angle of entry of the thyrights in the rectifiers. The means of measurement may also be confused with the means of regulation.

The means of measuring the current supply as well as the means (a) and (c) signals representing this current. These analog or numeric signals are preferably electrical. The means for measuring the current are associated with the calculation means (d). These connections are most frequently carried out by means of cables conducting electricity; but one does not exceed the scope of the invention by employing radio or infrared connections.

Measuring the current, the measurement (s) provided by the means (a), and the measurement (s) of the temperature (s) provided by the means (c) are connected to the calculating means (d) which perform the coherence processing of these measurements; i.e. that the means of calculation (d) by mathematical methods and by the laws of physics and chemistry, 10 applicable to electrolysis, compare these measurements with each other and correlate them with a partial system of numbers for the electrolysis cell, and determine the most probable values, measured values and other values which are not measured and which are calculated by calculation and which are also capable of providing an improved signal 15 (by means of these computational means (d)) which allows apply to the means of regulation, either by one of the velocities or by the current or by the temperature of the electrolysis. It is said that the computational means (d) carry out coherence treatments. The principle of coherence treatment will be explained in more detail below.

20

According to the invention, it is essential to measure the speed of one of the feed products or the waste products, for example, in the chlor-alkali electrolysis, the rate of the saline solution or the rate of water or the rate of sodium hydroxide can be selected. It is also crucial to measure the temperature of the electrolyte as well as the electric current on which all these measurements are calculated, possibly connecting them to physicochemical relationships which they must respect, e.g. For example, the amount of hydrogen formed may be associated with the current. The calculating means (d) provide at least one control signal which can apply the means for controlling the current or of one of the supply products or exhaust products or of the temperature. One can choose to regulate a supply product or a departure product different from that in which the measurement is used for the purpose of calculating the coherence state. Eg. the velocity of hydrogen upon departure from the cell, the temperature of the electrolyte, and the current may be used in the calculating means to output a signal which may affect the speed of the solution to be electrolyzed.

5

The calculating means (d) provide parallel to the signal that can be used for regulation, coherent values for velocities and for the current. It is also possible to fully understand the operating conditions of the electrolytic cell. The signal (s) used in the control means actually represent the order points of the various controllers. These signals represent the values of the velocity, temperature, or intensity that result from the coherence calculation and are one or more criteria to be determined, such as e.g. production maximum, or such value for the current that must not be exceeded etc ..

15 When examining the overall description sum, which comes from the coherence calculation and in accordance with various criteria, one can also influence the regulator (s) concerned, ie. manually modifying the order point of the controller (s) concerned.

In accordance with a preferred embodiment of the invention, a coherence treatment of multiple speeds could be introduced and proceed in such a way that the computational means (d) provide multiple control signals which can be applied to one or more of the elements of the group consisting of the means. (b) for controlling the speeds, a means for controlling the current and a means for controlling the temperature.

The coherence treatment is explained below in more detail from a calculation example.

30 A conduit is considered to carry a non-compressible fluid, and this conduit is provided with two mass velocity gauges A and B.

7 DK 174442 B1

The speedometer A has a turbine recording unit, and the speedometer B has e.g. a gauge having a pressure reducing opening forming a pressure drop. At the same time, two devices are observed: 5 For the speedometer A the value mA = 100 For the speedometer B the value γπβ = 105.

Under these conditions, a single size measurement has been made by means of independent means which results in two values different from the true value of the measurement, which will hereinafter be referred to as M.

The constructor of A indicates that a series n test has been carried out on measurement M, which has given him a total Wa on the measurements of M.

15

The spreading type for the system WA is sA = 2 e.g. and the mean is M.

The overall result WA has a law for normal distribution, ie. the probability density of this law in a known manner is: 20 - i (_H - m \ 2 - p = -e 2U) 25

The designer of the apparatus B indicates that he has also performed a series of n experiments at the speed M and that he has obtained the total system of Wb for the measurements of M.

The spreading type of the system WB is sB = 4 e.g. and the mean is M.

This system also has a probability density: 5 8 DK 174442 B1 - 1 / m - m \ 2 -j = r * € 2 \ 1B '

SB \ F

In the total system WA, the probability of obtaining a value m'A is as close as possible to the value mA, which can be expressed by the expression: 10 Sands. (m -dm / 2 <m '- ^ m. + dm / Z) = 1, e _ 1 / M ""' A2 AA Λ --- __ J -: - 1 dm SA nP '2 V SA / where dm is the differential element of the variabie m.

15 In the total system WB, the probability of obtaining a value m'B is as close as possible to the value mB to express by the equation: (dg-dm / 2 <m '^ n ^ + dm / 2) = 1. € - ^ ~ m <A ^ 20 SB ^ 2 [1B / 'When two events A and B are independent, the composite probability of seeing this is realized at once A and B the expression: 25 Sands. (ΑΠ B) = sands. (A) x sands, (B)

The following variables are replaced:

M - mV x. A

A --- s.

30 A

M - ra * XB = —- °

B

9 DK 174442 B1

The probability of the simultaneous implementation in the systems Wa and Wb of the values πΥα and m'B respectively as close as possible to the observed values πγ> α and mB can be expressed by: 5 Sands. [(mA-dm / 2 <m 'A <niA + dm / 2) BUE (mB-dm / 2 <m'B <mB + dm / 2] 2 2 fl 2 \ -X -X -K + X j _A _B _ ^ _ A_E / dm ^ _ .e 2 2 _ e_ 2.

2ti, Sa.Sb 2i .SA-SB

The examination of the analytical term, which gives a quantitative representation of the desired probability, shows that the probability 15 grows in a monotonous way when the term: 2 2 X + x _a_ ± decreases.

2 20

Put another way: the probability of simultaneously obtaining the values mA and mB in the systems WA and Wb is maximum when the expression: 2 2 25 x + x A B ...

- is at a minimum.

2 When: 30 2 2 x + x

_A_JB

2 10 DK 174442 B1 is at a minimum the most likely values for rftw and for mB: mA = nu + SaXa = M + mA - m'A 5 rnB = mB + SbXb = M + mB - m's.

Since the appliances A and B measure a single size M, one must look for the similarity between the values mB and mB.

10

One denotes y = γπα-γπβ as the expression of the logical coherence of the calculations of m. The numerical problem is thus simultaneously calculated:

X2 + X2 AB

- minimum under the requirement y = 0.

2

Since y = 0, it is equivalent to minimizing the auxiliary function 20 X2 + X2 z = A B + k.y 2 25 wherein k is a new unknown in the problem, which is referred to as the Lagrangemul multiplier.

The function z has an extreme when the derived functions with respect to XA and XB 30 are abolished, ie: dz

- = 0 dxA

11 DK 174442 B1 dz - =: o 5 5xb When all calculations have been performed, these two equations have the expression system: 10 XA + KSa = o (1)

Xb - KSb - 0

Thus, the variables XA and Xb which are replaced by the term for the context 15 (mA + SA X a = mB + SbXb) lead to 10: ksi + ksb "" a '% ie.

20 k mA - · «Β s2 + s2

SA + SB

The value of k entered in the system (1) gives: x. -: sA- (mA - v 25 s2 + s2

A

Xp - SB · <° A ~ V

30 and finally: 12 DK 174442 B1

SI - <"A" V

sA —A - -

SA + SB

SB - (“Α” V

5 -j—

S. ·. + SB

The numerical application of the results obtained above is: 10 mA = 100 - * 0 °° - 105) = i oo + 1 = 101 4 + 16 105+ 16 (1Q ° - 105> - 105-4 = 101 4 + 16 15

The most likely value for M (and not the value that is most certainly the closest one) is equal to 101.

The coherent values for the measurements πία and γπβ are: 20 mA = niB = 101

The certainty of obtaining values m which is closer to the total value than the untreated values m is obtained by multiplying the repetitions 25 of the raw measurements and processing them.

The reduction of the error is 50% on the measurement of A and 66% on the measurement of B in the case where the true value is equal to 102 and the remaining error on B then changes direction.

30

The efficiency of the processing of the material increases with the number of repetitions of the raw measurements and with the number of repeated calculation treatments and also with the precision and / or absolute errors of the measurements. The coherence calculation can be extended to any number of raw measurements subject to a certain number of restrictions, assuming, of course, that the number of restrictions is less than the number of measurements. One can, for example. apply the method described by G. V. REKLAITIS, A. RAVINDRAN and K. M.

5 RAGSDELL in "Engineering Optimization, Methods and Applications", John Wiley and Sons 1983, pages 184-189. The coherence calculation thus takes e.g. the preservation of the atoms in a chemical reaction, the preservation of the heat account, the preservation of the electrons, of the fillers or of the electrochemical numerical composition.

10

According to another embodiment of the invention, the signal improved by coherence processing is applied directly to at least one of the elements of the group consisting of the speed control means (b), the current control means and the temperature control means. This compound is made with the same agents, e.g. the connection between the means of measurement (a) and the calculating means (d), and these are analog, numerical, electrical or pneumatic bonds, or a mixture of these techniques, e.g. as a result of distances and of the necessary forces for the signals to influence the regulators. According to another form of the invention 20, computational means (d) are not used at all directly as a means of regulation.

One can, for example. have a direct control of a feed rate and a signal which affects the temperature at the input of the electrolyte and is manually modified as the set point for this input temperature of the electrolyte.

25

According to another preferred form of the invention, the electrolytic cell may comprise measuring means (e) which provide signals for measuring the contents of at least one of the products selected from the feed products and the exit products and these signals are associated with the calculating means 30 (d).

By the term "content" is meant the concentrations in the case of a liquid phase or the pH or the concentration or partial pressure in the case of a gas phase. It is not necessary to measure all the concentrations in a feed product or a waste product; know sufficiently by the chlor-alkali electrolysis to know the content of oxygen in the chlorine at the exit.

This means adds to the previous measurements, ie. the speed of one of the feed products or the waste products, the temperature of the electrolyte and the current, thereby improving coherence. According to another preferred form of the invention, one can measure the contents of other feed products and exit products or several contents of one of the products or simply a content of another product. For example, when In the case of the chlor-alkali electrolysis, it is preferable to measure oxygen in chlorine, and at the same time sodium hydroxide and chloride in the starting product of the cell.

According to another preferred form of the invention, the calculating means (d) may also provide one or more signals which are improved by the coherence processing and which may be used in connection with the means for adjusting an element in the content of a feed product or a waste product. One can, for example. modifying the content of the feed product of a compound to be electrolyzed by adding a diluent or a pure product to be electrolysed to increase its content. Thus, e.g. In the chlor-alkali electrolysis, sodium chloride is added to the feed product to increase the concentration of chloride or to add water to lower this concentration, and the pH therein may also be modified. Just as with the supply products or the waste products, one can measure a content and regulate the content of another, or possibly the same, either by means of another input product or a waste product. The calculating means (d) can also provide signals that can be used as well as signals that can be used directly.

According to another preferred embodiment of the invention, the cell may comprise means for measuring (f) at least one parameter selected from the pressure and temperature, this parameter being related to at least one of the elements of the group consisting of the feed products, the exit products and the various cells of the cell. B1 section, and in that these means of measurement (f) are associated with the means of calculation (d).

Of course, these temperatures do not relate to the temperature of the electrolyte in the electrolyte cell which is constantly taken into account.

According to another preferred form of the invention, the cell may comprise means for regulating (g) at least one parameter selected from the pressure and temperature, said parameter relating to at least one of the elements of the group consisting of the feed products, the exit products. These calculating means (d) provide signals for regulation, some useful by means of regulation (g), and others applied directly to the means (g).

The pressure or temperature controlled by a signal derived from the computational means (d) may be that measured or otherwise. Thus, for example, measure the temperature of the feed product to be electrocuted, take this measurement into account for coherence calculation and control with a signal enhanced by coherence calculation and emitted from the calculating means the pressure of a gas emanating from one of the electrodes.

20

The present invention is particularly useful in the chlor-alkali electrolysis.

In the intended use of the control device according to the invention, experience has shown that the coherence treatment carried out on the values 25 for the contents of the measured currents and the current strength enable a function of this system with the optimum yield. In the prior art plants which do not use this coherence treatment in this type of use, and which in particular do not, by means of coherence, process the values of the rate of the reaction components at the feed as well as the current, and optionally the values of the contents of these compounds at the outlet, the yield is clearly lower.

16 DK 174442 B1

The present invention is particularly useful in the case of an electrolysis method with a membrane in that the flow of hydrogen can be directly connected to the flow of electrons.

5 The calculation means also provide the intermediate steps in the calculations and, above all, the most probable values, which can thus be compared with the measured values. Their differences are expressed in terms of a correction coefficient. The inclusion of these correction coefficients permanently allows the function of the cell (or of the cell system) to be routed while preserving the mastery of the method.

The following example illustrates a chlor-alkali electrolysis cell according to the membrane process.

17 DK 174442 B1

MEASURED VALUES

Rate of salt solution at the entrance (l / h) 950 5 Temperature salt solution at the entrance (° C) 44

Concentration of NaCl

at the entrance (g / 1) 303.8

Concentration of sulphate at the entrance (in SO4) (g / l) 2.9

Concentration of NaOH at the entrance (g / l) 0.22

The concentration of Na 2 CO 3 at the input (g / l) 0.87 pH at the input 8

The rate of sodium hydroxide / water at the entrance (1 / h) · 74

Sodium hydroxide / 20 water temperature at the inlet (° C) 40

The concentration of sodium hydroxide / water at the entrance (% mass) 0.0001

The rate of sodium hydroxide 25 at the output (l / h) 229

Sodium hydroxide temperature at the outlet (° C) 84 concentration of sodium hydroxide at the outlet (% mass) 33.1 30

Speed of the slat solution at the output (l / h) 765

Temperature of the saline solution 18 at the outlet (° C) 82

Concentration of the salt at the outlet (g / l) 209.1 5 Concentration of the sulfate (in SO4) at the outlet (g / l) 3.6

Concentration of CLO (in CLO) at the output (g / l) 1.99

Concentration CLO3 (in CLO3) at the end (g / l) 0.16 pH at the end 3.9

Oxygen in chlorine (% volume) 2.4

Current in the cell (k-amp) 70.5 15 Voltage across the cell (Volt) 3.43

Pressure at the output H2 (mm water column) 40 Pressure at the output Cl2 (mm water column) 20 20 Ambient temperature (° C) 25

Relation between the relative error of the measurement of the current and the errors relative to the other currents 0.1 25 19 DK 174442 B1

Current measured "DBMA" and Needle Coherence Difference corrected Measured errors in values in% "DBMAC" values%% 5 No, 1: Current strength in amps 75000.0 0.5 70453.6 0.065

No. 2: Water in the brine at the entrance g / h 831375.4 5.0 869903.7 -4.634

No. 3: salt in saline at the input g / h 288610.0 5.0 302221.7 -4.716

No. 4: sulphate 15 in brine at the entrance g / h 4075.1 5.0 4074.8 0.006

No. 5: HCl in the saline solution at the inlet 2 g / h 0.0 5.0 0.0 0.000

No. 6: Sodium hydroxide in the brine at the entrance g / h 209.0 5.0 209.0 0.007 25 No. 7: Carbonate in the brine at the entrance g / h 826.5 5.0 826.7 0.035

No. 8: Water in the brine at 30 g / h 680939.8 5.0 669913.4 1.619

No. 9: Salt in the saline solution at the exit g / h 159961.5 5.0 157264.5 1.685 35 No. 10: Chlorine dissolved in salt solution at the end g / h 156.1 5.0 156.1 -0.025 DK 174442 B1 20

Forts.

No. 11: Sulfate in the brine at the exit g / h 4073.6 5.0 4074.8 -0.029

No. 12: Chlorate in the saline solution at the exit g / h 489.7 5.0 490.0 -0.057

No. 13: hypochlorite in the saline solution at the exit 10 g / h 1551.9 5.0 1555.4 -0.227

No. 14: HCl in the saline solution at the exit g / h 3.5 5.0 3.5 0.000 <r Nr. 15: Supply of water / sodium hydroxide rate of water g / h 73790.5 5.0 73535.9 0.345

No.16: Supply of water / sodium hydroxide rate sodium hydroxide g / h 0.0 5.0 0.0 0.345

No.17: Production of sodium hydroxide rate of water g / h 208252.1 5.0 201893.2 3.053

No. 18 Production of Sodium Hydroxide 30 Speed na Triumph Hydroxide g / h 5.0 99890.3 3.053

No.19: Production H „speed of entrained water 35 g / h 8087.1 5.0 8081.8 0.065 21 DK 174442 B1

Forts.

No.20: Production H £ h s-tighea high hydrogen g / h 2630.2 5.0 2628.5 0.065

No.21: Production Cl-5-density water entrained g / h 16704.4 5.0 17198.3 -2.956

No.22: Production CI2 rate chlorine g / h 84037.1 5.0 86368.2 -2.773 10 -----

No.23: Production CI2 rate oxygen g / h 909.0 5.0 913.1 0.454

No.24: production Cl_ has-CO 2 g / h * 343.0 5.0 343.1 0.036 20 25 1 35 22 DK 174442 B1

RECONSTRUCTION OF THE COHESIVE TREATED CURRENTS

Current in cell 70554 amps

Faraday yield at the cathode 95.01% 5 Faraday yield at the anode 92.56%

Faraday yield at the anode 95.34% after chlorination

Saline at entry corrected

Rate 994.0 l / h 10 NaCl concentration 304.0 g / l sulfate concentration (in SO4) 2.77 g / l

Saline outlet corrected

Speed 752.6 l / h Concentration NaCl 209.0 g / l

Concentration of sulphate (in SO4) 3.66 g / l

Concentration of chlorate (as ClO 3) 0.163 g / L

Concentration CLO (in CLO) 2.03 g / l 20 Supply of sodium hydroxide / water corrected Rate of sodium hydroxide / water at the input 73.7 1 / h

Sodium hydroxide concentration at the input 0.0% 25

Output of sodium hydroxide corrected Rate of sodium hydroxide at exit 222.0 l / h

Concentration of sodium hydroxide 30 at exit 33.10%

Purity of chlorine

Percentage of oxygen in chlorine 2.33% 23 B1

Production of the cell

Rate of chlorine at the cell boundary 86,368 kg / h 5 Speed of chlorine total 88,962 kg / h

Production of 100% NaOH 99,890 kg / h

Hydrogen production 2,629 kg / h HCl for chlorination 1.08 kg / h as 100% 10 Electricity consumption

Production NaOH A 2419.0 kwh / ton as 100%

Production of chlorine A 2716.0 kwh / ton as total chlorine

In this example, only the results of the coherence calculation have been shown. For reasons of clarity, it is not possible to show the variations in these parameters over time. The coherence-treated values can influence certain set points on the regulators. In this case as used, one chooses to control the rates and temperature of the brine solution at the inlet as well as the rates and temperature of the supply of water.

Another advantage of the invention is found here, namely that by studying the relative differences one can find out which measurement shows wrong results and which should be repaired.

25

Claims (5)

A method for regulating an electrolysis cell comprising: a) means measuring and providing measurement signals for the rate of at least one of the feed products or of at least one of the output products; b) any means controlling the rate of at least one of the feed products; (c) at least one means of measuring the temperature of the electrolyte and optionally at least one of the means of regulating that temperature; (d) calculating means associated with the means of measuring (a) the velocities and of means of measuring (c) of the electrolyte; temperature, characterized in that: (20) the calculating means (d) are associated with at least one current measuring the current, and (ii) the calculating means (d) conducting coherence treatments of the speed measurements provided by the means (a) and of the current measurement, and 25 (iii) the computational means provide at least one signal which is improved through the coherence processing and which may be is turned on at least one of the elements of the group consisting of the speed control means (b), a power control means, and the temperature control means. 30 Method according to claim 1, characterized in that the computational means (d) provide at least one signal for direct control applied to at least one of the elements in the group consisting of the means (b) for controlling the velocity. 25 DK 174442 B1, a means for regulating the current and the means for regulating the temperature. Method according to claim 1 or 2, characterized in that the electrolyte cell comprises means for measuring (e) which provide signals for the measurement of the contents of at least one of the products selected from the supply products and the exit products and these signals are connected to the means of calculation (d). Method according to any one of claims 1-3, characterized in that the cell comprises means for measuring (f) at least one parameter selected from the pressure and temperature, such parameter being at least one of the elements of the group consisting of the feed products, the exit products. and the individual sections of the cell and that these means for measurement (f) are associated with the computational means (d). Process according to any one of claims 1-4, characterized in that it is applied to a chlor-alkali electrolysis cell.